[vsnet-outburst 25414] ZTF20ablyczu: large-amplitude dwarf nova (ATEL)

[Taichi Kato]

ZTF20ablyczu: large-amplitude dwarf nova (ATEL)

ATEL #13883							     ATEL #13883

Title:	Spectroscopic confirmation of AT 2020plo (M31 recurrent nova
		candidate) as a Galactic dwarf nova
Author:	S. C. Williams (Turku), M. J. Darnley (LJMU), F. J. Murphy-Glaysher
		(LJMU)
Queries:	steven.williams at utu.fi
Posted:	21 Jul 2020; 11:24 UT
Subjects:Optical, Cataclysmic Variable, Nova, Transient

We obtained a spectrum of the transient AT 2020plo (ZTF20ablyczu; ATel
#13869) with the SPRAT spectrograph (resolution R ~ 350; <a href="http://adsabs.harvard.edu/abs/2014SPIE.9147E..8HP">Piascik
et al. 2014</a>) on the 2-m Liverpool Telescope (LT; <a href="http://adsabs.harvard.edu/abs/2004SPIE.5489..679S">Steele
et al. 2004</a>) on 2020 Jul 21.17 UT.   

The spectrum shows a blue continuum, along with absorption from Hβ,
Hγ and Hδ. The absorption-line minima are consistent with z=0.
This spectrum indicates that AT 2020plo is not an M31 recurrent nova, but
a foreground Galactic dwarf nova in outburst. We will aim to obtain an
additional epoch of spectroscopy later in the outburst. The ZTF light curve
(obtained via Lasair) indicates that the outburst peaked at g = 15.11 +/-
0.02. The lack of a clear source in deep PanSTARRS-1 imaging (<a href="https://ui.adsabs.harvard.edu/abs/2016arXiv161205243F">Flewelling
et al. 2016</a>) implies a g-band outburst amplitude of ≳6.5 mag.
The optical observations so far are consistent with a WZ Sge-type dwarf
nova.